"You know, what happened, I liked him when I came in here because he wasn't a politician. But right now, he skirted around questions better than a lifelong politician ever had," one respondent told Republican pollster Frank Luntz, who conducted the focus group.

Added another respondent whom Luntz identified as Anthony: "I was really expecting him to do a lot better. But he just crashed and burned. He was mean, he was angry, he had no specifics, he was bombastic."

Before the debate, 14 voters on the panel said they had a favorable view of Trump. After the debate, only three said they still saw the reality-television personality positively.

Trump's refusal to pledge that he would back the eventual Republican nominee did not go over well with the Fox News panel, either.

"I was repulsed by it," one respondent said. "If he runs third party, Republicans lose. Period."

"It's a divide-and-conquer strategy, basically," another respondent said. "He's splitting the party. He's basically going to take away focus from the candidate who's going to be leading."

On Twitter, Michael Cohen, an executive vice president at and special counsel to Trump's organization, took aim at Luntz and at Fox.

Some polling analysts pointed to the focus group as an example that many voters haven't been paying much attention to the election, which they have suggested may be inflating Trump's poll numbers. The consensus among pollsters is that Trump's high name recognition has helped him shoot to the front of the pack.